When climate expert Veerabhadran “Ram” Ramanathan, PhD, came to the United States in 1970 from his home in India, climate change was the furthest thing from his mind.

“I didn’t come here for studies. I didn’t come here for research,” said Ramanathan, during a talk at Creighton on Wednesday.

“This was my dream,” Ramanathan said, flipping to a slide of a blue Chevy Impala, to laughs from the crowd.

But Ramanathan traveled a different road. After earning his PhD at the State University of New York at Stony Brook, Ramanathan took a job at NASA, and was part of a team that launched the first climate satellite – measuring the effects of greenhouse gases.

An expert in the physics and chemistry of the atmosphere, he has met with three popes – St. John Paul II, Benedict and Francis. Ramanathan has spoken with both Pope Benedict and Francis about climate change, and his work on the Pontifical Academy of Sciences helped inform the scientific basis for Pope Francis’ 2015 encyclical on the environment and human ecology, Laudato Si’. He continues to work with the Vatican, and is known informally as “the Pope’s climate scientist.”

Ramanathan’s lecture, before a full Ahmanson Ballroom in the Harper Center, was titled “Climate Change: Morphing into an Existential Threat” and was hosted by the Creighton Global Initiative as part of the Planetary Emergency Lecture Series. Three more lectures are planned for 2018 and 2019.

“If there is really one thing I would like you to remember, it’s this: Climate change can reach crisis levels in a few decades,” Ramanathan said. “In fact, all the students who are sitting here, I predict this is the major problem you are going to be facing. So, it’s an urgent problem, requiring urgent solutions.”

He then presented an overview of the science of how he came to that conclusion – starting with the carbon dioxide produced by the burning of fossil fuels, which includes our cars’ emissions.

“It is the most insidious gas you can ever think of,” he said, “primarily because it doesn’t die. Whatever you emit today from the tailpipe, half of it will be here 100 years from now."

And 20 percent, he continued, will stay in the atmosphere for 1,000 years or more.

Carbon dioxide emissions cover the Earth like a blanket.

“It traps the heat from the Earth, and from the atmosphere,” he said. He estimates that 2 trillion tons of carbon dioxide have been released into the atmosphere over the last nearly 300 years. “And 45 percent of that is still there. That’s 950 billion tons of junk in the air.”

Carbon dioxide and other invisible greenhouse gasses are quickly pushed around the globe by the earth’s winds.

“It takes just five days for pollution emitted in China to reach the U.S.,” he said, with pollution from the U.S. hitting Europe in two and a half days, and the circle continuing. “That’s how we are all connected,” he said, adding: “We are never going to solve this problem by pointing fingers. It’s the Chinese doing it. It’s the Americans doing it. It’s India. We just have to assume we are family, and how do we get out of this mess?”

He painted a bleak picture of deadly heat waves, extreme droughts (lasting 10 to 30 years) and mass extinctions in the next 50 years if nothing is done. He added that we could exceed the threshold for dangerous climate change in the next 15 years.

But, he added, “It’s not too late.” Catastrophic destruction is not inevitable, he said, but the clock is ticking.

Ramanathan, a distinguished professor of atmospheric and climate sciences at the Scripps Institution of Oceanography in the University of California system, leads that university’s Bending the Curve Initiative, which is developing 10 solutions to the climate change problem. He addressed two during his talk.

“We basically have two levers to bend the curve,” Ramanathan said. “The first is the carbon lever. Remarkably, the solution is very simple. What we need to do is bring the carbon emission to zero, and the way we are going to do that is by replacing fossil fuels” with electricity – from solar, wind, geothermal, hydro and, “if need be,” nuclear sources.

Attacking short-lived climate pollutants is another lever. Soot and methane, for instance, are two examples of major global warming agents that dissipate much faster than carbon dioxide. “We have technologies to bend them. If we do that, say starting two years from now, we can cut down the rate of warming very quickly – in 20 years, by half. So that will give us time.” (His proposal to limit these pollutants has recently been adopted by the UN and 30 countries, including the United States.)

But, Ramanathan said, it’s not just a technology issue – it’s also a moral issue.

“We are causing irreversible changes on a thousand-year timescale,” he said. “And we are giving this shared home to our children quite a bit damaged. What did they do to deserve this?

“Secondly, 50 to 60 percent of the pollution comes from the wealthiest 1 billion (people on earth). And the poorest 3 billion will suffer the worst consequences.”